The present invention relates to an electro-plating barrel, and more particularly to such an electro-plating barrel which uses a speed increaser driven by the barrel to turn a vane pump causing it to pump plating solution into the barrel so as to equalize the concentration of the plating solution internally as well as externally.
U.S. Pat. No. 4,946,573, issued to the present inventor, discloses a pump-attached dipole electro-plating barrel, which includes an impeller vane pump driven by the barrel to constantly pump outside plating solution into the barrel so as to equalize the concentration of the plating solution internally as well as externally. Several electrodes are positioned in the barrel to alternatively connect with with anode and cathode through an electric polarity changing device, so that the metal film which is deposited onto the electrodes during the rotation of temporary cathode can be automatically electrolyzed from the electrodes through the change of electric polarity connection to minimize the consumption of anode metal and metal ion in bath. This structure of electro-plating barrel is functional, however, due to the limitation of the ratio of number of teeth between the end gear portion on the barrel and the driven gear on the impeller vane pump, the revolving speed of the axle of the vane-like member of the impeller vane pump is limited. Therefore the operation efficiency of this structure of electro-plating barrel must be improved.